4.
IS : 2911 ( Part l/Set 4 ) - 1984
Indiun Standard
CODE OF PRACTICE FOR DESIGN
AND CONSTRUCTION OF PILE FOUNDATION
PART 1 CONCRETE PILES
Section 4 Bored Precast Concrete Piles
0. FOREWORD
0.1 This Indian Standard ( Part l/Set 4 ) was adopted by the Indian
Standards Institution on 27 February 1984, after the draft finalized
by the Foundation Engineering Sectional Committee had been approved
by the Civil Engineering Division Council.
0.2 Piles find application i.n foundation to transfer loads from a structure
to competent subsurface strata having adequate load-bearing capacity. The
load transfer mechanism from a pile to the surrounding ground is complic-
ated and could not yet be fully determined, although application of piled
foundations is in practice over many decades. Broadly, piles transfer axial
loads either substantially by friction along its shaft and/or substantially
by the end bearing. Piles are used where either of the above load transfer
mechanism is possible, depending upon the subsoil stratification at a parti-
cular site. Construction of pile foundations requires a careful choice of
piling system, depending upon the subsoil conditions, the load characteris-
tics of a structure and the limitations of total settlement, differential settle-
ment and any other special requirement of a project. The installation of
piles demands careful control on position, alignment and depth and involve
specialized skill and experience.
0.3 This standard ( Part 1 ) was originally published in 1964 and included
provisions regarding driven cast in-situ piles, precast concrete piles, bored
( cast in-situ ) and under-reamed piles, including load testing. Subsequently
portions pertaining to under-reamed pile foundations were deleted and which
are now covered in IS : 2911 ( Part 3 ). At that time it was decided
that the provisions regarding other types of piles should also be published
separately for the ease of reference and to take into account the recent
developments in this field. Consequently IS : 2911 ( Part 1 )-1964* has
*Code of practice for design and construction of pile foundation: Part 1 Load bearing
concrete piles.
3

5.
IS : 2911 ( Part l/Set 4 ) - 1984
been revised in various sections. So far the following sectiops have been
formulated.
Section 1 Driven cast in-situ concrete piles
Section 2 Bored cast in-& piles
Section 3 Driven precast concrete piles
Section 4 Bored precast concrete piles
0.3.1 This section covers the bored’ precast concrete piles which have
now come into use in recent times.
0.4 Bored precast concrete pile is a pile constructed in a casting yard and
subsequently lowered into pre-bored holes and the space grouted. These
piles find wide applications where safety against chemical aggressive subsoil
and the ground water condition is needed. Such protection is possible with
bored precast concrete piles, because these are made using vibrated dense,
matured concrete, with low water cement ratio and are not subjected to
driving stresses. These are also useful where artesian conditions exist or
where local obstructions are encountered above the founding level or
subsoil water flow exists. They also offer facility for applying protective
coating on the pile surfaces. The provision in respect of segmental piles
with properly designed joints are under consideration of the Committee
and its provisions will be covered at a later stage.
0.5 The Sectional Committee responsible for the preparation of standard,
while formulating this standard, gave due consideration to the available
experience in this country in pile construction and also the limitations
regarding the availability of piling plant and equipment.
0.5.1 The information furnished by the various construction agencies
and specialist firms doing piling work in this country and technical discus-
sions thereon considerably assisted the committee in formulation of this
code.
0.6 For the purpose of deciding whether a particular requirement of this
standard is complied with, the final value, obierved or calculated, express-
ing the result of a test, shall be rounded off in accordance with IS : 2-1960*.
The number of significant places retained in the rounded off value should
be the same as that of the specified value in this standard.
*Rules for rounding off numerical values ( rcuised ).
4

6.
ISt2911(Partl/Sec4)-1984
1. SCOPE
1.1 This standard ( Part l/Set 4 ) covers the design and construction of
load bearing bored precast concrete pile which transmit the load of the
structure to the strata where resistance is adequate.
NOTE- This standard is based on assumption that strength of grout fill up in
the space shall be at least equivalent to that of surrounding soil and the skin friction
developed on the pile shall be determined by probative test.
2. TERMINOLOGY
2.0 For the purpose of this standard, the following definitions shall apply.
2.1 Allowable Load - The load which may be applied to a pile after
taking into account its ultimate load capacity, pile spacing, overall bearing
capacity of the ground below the pile, the allowable settlement, negative
skin friction and the loading conditions including reversal of loads, etc.
2.2 Batter Pile ( Raker Pile )
to the vertical.
- The pile which is installed at an angle
2.3 Bearing Pile - A pile formed in the ground for transmitting the load
of a structure to the ‘soil by the resistance developed at its tip and/or along
its surface. It may be formed either vertically or at an inclination ( Batter
Pile ) and may be required to take uplift.
If the pile support the load primarily by resistance developed at the
pile point or base it is referred to as 6End Bearing Pile ‘, if primarily by
friction along its surface then as ‘ Friction Pile ‘.
2.4 Bored Precast Pile - A pile constructed in reinforced concrete in
a casting yard and subsequently lowered into prebored holes and space
grouted.
2.5 Cut-off Level - It is the level where the installed pile is cut-off to
support the pile caps or beams or any other structural components at that
level.
2,6 Factor of Safety - The ratio of the ultimate load capacity of a pile,
to the safe load of a pile.
2.7 Safe Load -The load derived by applying a factor of safety on the
ultimate load capacity of the pile or as determined in the load test.
2.8 Ultimate Load Capacity - The maximum load which a pile or pile
shaft can carry before failure of ground ( when the soil fails by shear as
evidence from the load settlement curves ) or failure of pile materials.
2.9 Working Load - The load assigned to a pile according to design.
5

7.
IS : 2911 ( Part l/Se!c 4 ) - 19S4
3. NECESSARY INFORMATION
3.1 For the satisfactory design and construction of bored precast piles, the
following information is necessary:
a) Site investigation data as laid down in IS : 1892-1979*, and other
relevant Codes. Sections of trial boring, supplemented, wherever
appropriate, by penetration tests, should incorporate data/infor-
mation sufficiently below the anticipated level of the pile tip; the
boring below the pile tip should generally be not less than 10 m
unless bed rock or firm strata has been encountered earlier. The
nature of the soil both around and beneath the proposed pile
should be indicated on the basis of appropriate tests of strength,
compressibility, etc. Ground-water levels and conditions ( such
as artesian conditions ) should be indicated. Results of chemical
tests to ascertain the sulphate and chloride content and/or any
other deleterious chemical content of soil and/or ground water
should be indicated, particularly in areas where large piling work
is envisaged or where such information is not generally available.
b) In case of bridge foundations, data on high flood level, maximum
C>
4
e)
f-1
s)
scouring depth, normal water level during working season, etc,
should be provided. In the case of marine construction, high and
low tide level, flow of water and other necessary information, as
listed in IS : 4651 ( Part 1 )-19741_ should be provided.
In case rock is encountered, adequate description of rock to convey
its physical conditions as well as its strength characteristics should
be indicated.
General plan and cross section of the structure showing type of
structural frame, including basement, if any, in relation to the
proposed pile-cap top travels should be provided.
The general layout of the structure showing estimated loads, verti-
cal and horizontal, moments and torque at the top ofpile caps,
but excluding the mass of the piles and caps should be provided.
The top levels of finished pile caps shall be clearly indicated.
All transient loads due to seismic and wind conditions and load
due to under water should be indicated separately.
Sufficient information of structures existing nearby and the experi-
ence of piles in the area close to the proposed site and boring. _
report thereof for assessing the founding level of piles should be
provided.
*Code of practice for subsurface investigations for foundations ( Jirst revision).
tCode of practice for planning and design of ports and harbourr: Part 1 Site investi-
gation ( jirst revision ).
6

8.
IS : 2911( Part l/!&c 4 ) - 1984
4. EQUIPMENT AND ACCESSORIES
4.1 The equipment and accessories will depend on the type of bored pre-
cast piles chosen in a job and would be selected giving due consideration
to the subsoil strata, ground-water conditions, type and founding material
and the required penetration therein wherever applicable.
4.2 Among the commonly used plants, tools and accessories, there exist a
large variety; suitability of which depends on the subsoil conditions,
manner of operation, etc.
Boring operations are generally done by any appropriate method
with or without temporary casing. Boring may be carried out using mud
stabilisation if required.
4.3 Handling Equipment for Lowering - Handling equipment such
as crane, derricks, movable gantry, may be used for handling and lower-
ing of the precast piles in the bore. The choice of equipment will depend
upon length, mass, and other practical requirements.
4.4 Grouting Plant - The mixing of the grout can be carried out in any
suitable high speed collidal mixer. For grouting a suitable grout pump
with stirring/agitating arrange.ment may be used.
5. DESIGN CONSIDERATION
5.1 General - Pile foundations shall be designed in such a way that the
load from the structure it supports, can be transmitted to the soil without
causing any soil failure and without causing such settlement differential or
total under permanent transient loading as may result in structural damage
and/or functional distress. The pile shaft should have adequate structural
capacity to withstand all1 oads ( vertical, axial or otherwise ) and moments
which are to be transmitted to the subsoil and shall be designed according
to IS : 456-1978*. The shaft of bored precast piles may be of circular or
octagonal shape, and may be of solid Section or with a central hollow core.
The limiting size of the pile will depend mainly on available handling
equipment and the mass of the pile shaft to be handled.
5.2 Adjacent Structures
5.2.1 When working near existing structures care shall be taken to avoid
any damage to such structures. In the case of bored pile care shall be
taken to avoid effect due to loss of ground; when boring is carried out
using mud, the stability of the bore particularly adjacent to loaded founda-
tions shall be examined.
5.2.2 In case of deep excavations adjacent to piles, proper shoring or
other suitable arrangement shall be done to guard against the lateral move-
ment of soil stratum or releasing the confining soil stres:.
*Code of practice for plain and reinforced concrete ( fhird rat&ion ).
7

9.
IS t 2911( Part l/Set 4 ) - 1984
5.3 Soil Resistance - The bearing capacity of a pile is dependent on
the properties of the soil in which it is embedded. Axial load from a pile
is normally transmitted to the soil through skin friction along the shaft and
end bearing at its tip. A horizontal load on a vertical pile is transmitted
to the subsoil primarily by horizontal subgrade reaction generated in the
upper part of the shaft.
along its axis.
A single pile is normally designed to carry load
Transverse load bearing capacity of a single pile depends
on the soil reaction developed and the structural capacity of the shaft
under bending. In case the horizontal loads are of higher magnitude, it
is essential to investigate the ‘phenomenon using ‘principles of horizontal
subsoil reaction adopting appropriate values for horizontal modulus of the
soil. Alternatively piles may be installed in rake.
5.3.1 The ultimate load capacity of a
suitable static formula. However, it shoul B
ile may be estimated using a
preferably be determined by
an initial load test [ see IS : 2911 ( Part 4 )-1984 ]*. The cross sectional
asea for the purpose of the calculation shall be the’ concrete section
excluding the grout where chemical aggression is likely to inhibit setting
of cement.
The settlement of pile obtained at safe load/working load from load
test results on a single pile shall not be directly used in forecasting the
settlement of structure [ see IS : 8009 ( Part 2 )-198@ 1.
The average settlement may be assessed. It would be more appro-
priate to assess the average settlement on the basis of subsoil data and
loading details of the structure as a whole using the principles of soil
mechanics.
5.3.1.1 Static formula - By using static formula, the estimated value
of ultimate load capacity of a typical pile is obtained, the accuracy being
dependent on the reliability of the formula and the reliability of the
available soil properties for various strata. The soil properties to be
adopted in such formula may be assigned from the results of laboratory
tests and field tests like standard penetration tests ( see IS : 2131-1981$ ).
Results of cone penetration tests may also be utilized where necessary
correlation with soil results data has been established [ see IS : 4968
( Part 1 )-19768 1, IS : 4968 ( Part 2 )-19768, IS : 4968 ( Part 3 )-19768.
Two separate static formula commonly applicable for cohesive and
*Code of practice for design and construction pile foundations: Part 4 Load test
on piles ( /ird rcoision).
iCode of practice for calculation of settlement of foundations: Part 2 Deep founda-
tions subjected to symmetrical static vertical loading.
$Method for standard penetration test for soils (~$rstr&ion ).
§Method for subsurfacesoundingfor soils:
Part I Dynamic method using 50 mm cone without bentonite slurry (first
revision ).
Part II Dynamic method using cone and bentonite slurry
Part III Static cone penetration test (/irst revision ).
(Jrsf revision ).
8

10.
IS: 2911 ( Part l/Set 4 ) - 1984
cohesionless soil respectively are indicated in Appendix A to serve only
as a guide. Other alternative formula may also be applicable, depending
on the subsoil characteristics and method of installation of piles.
5.4 Negative Skin Friction or Dragdown Force - When a soil
stratum through which a pile shaft has penetrated into ati underlying
hard stratum, compresses as a result of either it being unconsolidated or
it being under a newly placed fill or as a result of remoulding of the pile,
a dragdown force is generated along the pile shaft up to a point in depth
where the surrounding soil does not move downward relative to the pile
shaft.
NOTE- Estimation of this dragdown force is still under research studies and
considerations, although a few empirical approaches are in use for the same. The
concept is constantly under revision and, therefore, no definite proposal is embodied
in this standard.
5.5 Structural Capacity - The’ piles shall have necessary structural
strength to transmit the loads imposed on it, ultimately to the soil.
5.5.1 Axial Capacity - Where a pile is wholely embedded in the soil
( having a undrained shear strength not less than 0.1 kgf/cm* ) its axial
carrying capacity is not limited by its strength as a long columxi. Where
piles are installed through very weak soils ( having an undrained shear
strength less than 0.1 kgf/cm* ) special considerations shall be made to
determine whether -the shaft would behave as long column or not; if
necessary suitable reductions shall be made for its structural strength follow-
ing the normals tructural principles covering the buckling phenomenon.
When the finished pile projects above ground level and is not secured
against buckling by adequate bracing, the effective length will be governed
by fixity conditionsi mposed on it by the structure it supports and by the
nature of the soil into which it is installed. The depth below the ground
surface to the lower point of contraflexure varies with the type of the soil.
A stratum of liquid mud should be treated as if it was water. The degree
of fixity of the position and inclination of the pile top and the restraint
provided by any bracing shall be estimated following accepted structural
principles. The permissible stress shall be reduced in accordance with
similar provisions for reinforced concrete columns as laid down in
IS: 456-197g*.
5.5.2 Latefal Load Cafiack’y - A pile may be subjected to transverse force
from a number of causes, such as wind, earthquake, water current, earth
pressure effect of moving vehicles or ships, plant and equipment, etc. The
lateral load carrying capacity of a single pile depends not only on the
horizontal subgrade modulus of the surrounding soil but also on the
*Code of practice for plain and reinforced concrete ( t/u% revision).
9

11.
IS : 2911 ( Part l/Set 4 ) - 1984
structural SLength of the pile shaft against bending consequent upon applic-
ation of a lateral load. While considering lateral load of piles, effect of
other coexistent loads including the axial load on the pile, should be taken
into consideration for checking the structural capacity of the shaft. A
recommended method wherever possible for the determination of the depth
of fixity of piles required for design is given in Appendix R. Other accepted
methods such as the method of Reese and Matlock may also be used.
NOTE-Because of limited information on horizontal modulus of soil, and
refinements in the theoretical analysis, it is suggested that adequacy of a design
may be checked by an actual field load test.
5.5.3 Raker Piles - Raker piles are normally provided where vertical
piles cannot resist the required applied horizontal forces. In the preli-
minary design the load on a raker pile is generally considered to be axial.
The distribution of load between raker and vertical piles in a group may
be determined by graphical or analytical methods.
consideration shou d
Where necessary, due
1
be made for secondary bending induced as a result
of the pile cap moement, particularly when the cap is rigid. Free-standing
raker piles are sub]ected to bending moments due to their own mass, or
external forces from other causes. Raker piles embedded in fill or consolida-
ting deposits, may become laterally loaded owing to the settlement of the
surrounding soil.
5.6 Spacing of Piles - The centre-to-centre spacing of piles should be
considered from two aspects:
a) practical aspects of installing the piles, and
b) the nature of the load transfer to the soil and possible reduction
in the bearing capacity of a group of piles thereby.
The choice of the spacing is normally made on semi-empirical
approach.
5.6.1 In case of piles which are predominantly resting on hard stratum
and deriving their capacity mainly from end bearing, the spacing will be
governed by the competency of the end bearing strata. The minimum
spacing in such cases, shall be 2.5 times the diameter of the pile. In case
of piles resting on rock, the spacing of twice the diameter of the pile may
be adopted.
5.6.2 Piles deriving their bearing capacity mainly from friction shall be
sufficiently apart to ensure that the zones of soils from which the piles
derive their support do not overlap to such an extent that their bearing
values are reduced. Generally the spacing in such cases shall not be less
than three times the diameter of the pile.
5.6.3 The spacing should not be SOclose as to cause direct contact
between two adjacent piles in a group, the deviations at depths arising
out of the tolerance allowed in the installation. This would mean the
10

12.
i
IS : 2911 ( Part l/See 4 ) - 1984
minimum spacing would, to some extent, depend on the length of piles
installed.
5.7 Pile Grouping - In order to determine the bearing capacity of a
group of piles, a number of efficiency equations are in use. However, it is
very difficult to establish the accuracy of these efficiency equations as the
behaviour of piles group is dependent on many complex factors. It is
desirable to consider each case separately on its own merit.
5.7.1
a)
The bearing capacity of a pile group may be either:
equal to the bearing capacity of individual piles multiplied by the
number of piles in the group, or
b)
5.7.2
it may be less.
In case of piles deriving their support mainly from friction and
connected by a pile cap, the group may be visualized to transmit load t0
the soil, as if from a column of soil enclosed by the piles. The ultimate
capacity of the group may be computed following this concept, taking into
account the frictional capacity. along the perimeter of the column of soil
as above and the end bearing of the said column using the accepted
principles of soil mechanics.
5.7.2.1 When the cap of the pile group is cast directly on reasonably
firm stratum which supports the piles it may contribute to the bearing
capacity of the group. The additional capacity along with the individual
capacity of the piles multiplied by the number of piles in the group should
not be more than the capacity worked out in 5.7.2.
5.7.3 When a moment is applied on the pile group either from super
structure or as a consequence of unavoidable inaccuracies of installation,
the adequacy of the pile group in resisting the applied moment should be
checked. In case of a single pile subjected to moments due to lateral forces
or eccentric loading beams may be provided to restrain the pile cap
effectively from lateral or rotational movement.
5.7.4 In case of structure supported on single pile/group of piles, result-
ing into large variation in the number of piles from column to column, it
is likely, depending on the type of subsoil supporting the piles, to result in
a high order of differential settlement. Such high order of differential
settlement may be either catered for in the structural design or it may be
suitably reduced by judicious choice of variations in the actual pile load-
ings. For example, a single piles cap may be loaded to a level higher than
that of a pile in a group in order to achieve reduced differential settlement
between two adjacent pile caps supported on different number of piles.
11

13.
ISr2911(Part1/Sec4)-1984
5.8 Factor of Safety and Safe Load
5.8.1 Factor of safety should be judiciously chosen after considering:
a) the reliability of the value of ultimate load capacity of a pile,
b) the type of superstructure and the type of loading, and
c) allowable total/differential settlement of the structure.
508.2 The ultimate load capacity may be obtained whenever practicable,
from a load test ( initial ) [ see IS : 2911 ( Part 4 )-19&l* J.
5.8.3 When the ultimate load capacity is computed from static formula
the factor of safety would depend on the reliability of the formula depend-
ing on a particular site and locality and the reliability of the subsoil para-
meters employed in such computation.
static formula shall be 2.5.
The minimum factor of safety on
The final selection of factor of safety shall take
into consideration the load settlement characteristics of the structure as a
whole at a given site.
5.8.4 Factors of safety for assessing safe load on piles from load test
data should be increased in unfavourable conditions where:
b)
4
4
settlement is to be h&ted or unequal settlement avoided as in the
case of accurately aligned mechinery cr a superstructure with
fragile finishings,
large impact or vibrating loads are expected,
the properties of the soil may be expected to deteriorate with
time, and
the live load on a structure carried by friction piles is a consider-
able portion of the total load and approximates to the dead load
in its duration.
5.9 Transient Loading - The maximum permissible increase over the
safe load of a pile as arising out of wind loading, is 25 percent. In case
of loads and moments arising out of earthquake effects, the increase of
safeload on a single pile may be limited to the provisions contained in
IS : 1893-I975t. For transient loading arising out of superimposed loads
no increase may be generally allowed.
5.10 Overloading - When a pile in a group, designed for a certain safe
load is found, during or after execution, to fall just short of the load
required to be carried by it, an overload up to 10 percent of the pile
capacity may be allowed on each pile. The total overloading on the
*Code of practice for design and construction of pile foundations: Part 4 Load teat
on piles (first revision ).
tcriteria for earthquake resistant design of structures ( third revision ) .
12

14.
IS :, 2911 ( Part l/&c 4 ) - 1984
group should not be more than 10 percent of the capacity of the group and
not more than 40 percent of the allowable load on a single pile. This is
subject to the increase of the load on any pile not exceeding 10 percent of
its capacity.
5.11 Lifting and Handling Stresses - Stresses induced by bending
in the cross section of a precast pile during lifting and handling may be
estimated just as for any reinforced concrete section in accordance with
relevant provisions of IS : 456-1978*. The calculations with regard to
moments depending on the method of support during handling will be as
given below. Excessive whippiness in handling precast pile may generally
be avoided by limiting the length of pile to a maximum of 50 times the
least width.
Number of Points Location of Point of Sqfiort from Bending Moment
of Pick Up and in Tewns of Length of Pile for to be Allowed
Minimum Moments for Design
One
.
0.293 L
O-207 L
WL
23.3
WL
46.6
Three
where
O-145 L, the middle point
will be at the centre
WL
95
W = mass of pile in kg, and
L = length in metres.
During hoisting the pile will be suspended at one point near the
head and the bending moment will be the least when it is pulled in a
distance of 0,293 L, and the value of bending moment will be:
WL
23;3
5.12 Reinforcement - The longitudinal reinforcement shall be provided
in for the entire length preferably of high yield strength to withstand the
handling stresses to the extent to meet requirement as given in 5.11. All
the main longitudinal bars shall be of the same length. The area of the
main longitudinal reinforcement of any type and grade shall not be less
than O-4 percent of the cross section area of the piles or as required to
cater for handling stresses ‘whichever is greater. The lateral reinforce-
ment shall be links or spirals preferably of not less than 6 mm diameter
bars. The cover of concrete over all the reinforcement including bend-
ing wire should not be less than 40 mm, but where the piles are exposed
*Codeofpracticeforplainandreinforcedconcrete(third rmisien ).
13

15.
IS : 2911 ( Part l/Set 4 ) - 1984
to the sea water or water having other corrosive contents the cover should
be no where less than 50 mm. A thin gauge sheathing pipe of approxi-
mately 40 mm diameter may be attached to the reinforcement cage, in
case of solid piles, to form the central duct for pumping grout to the
bottom of the bore.
5.13 Design of Pile Cap
5.13.1 The piL caps may be designed by assuming that the load from
column is dispersed at 45” from the top of the cap up to the mid-depth of
the pile cap from the base of the column or pedestal. The reaction from
piles may also be taken to be distributed at 45” from the edge of the pile,
up to the mid-depth of the pile cap. On this basis the maximum bending
moment and shear forces should be worked out at critical sections. The
methods of analysis and allowable stresses should be in accordance with
IS : 456-1978*.
5.13.2 Pile cap shall be deep enough to allow for necessary anchorage
of the column and pile reinforcement.
5.13.3 The pile cap should normally be rigid enough so that the
imposed load could be distributed on the piles in a group equitably.
5.13.4 In case of a large cap, where differential settlement may be
imposed between piles under the same cap, due consideration for the
consequential moments should be given.
5.13.5 The clear overhang of the pile cap beyond the outermost pile
in the group shall normally be 100 to 150 mm depending upon the pile
size.
5.13.6 The cap is generally cast over a 75 mm thick levelling course of
concrete. The ‘clear cover for main reinforcement in the cap slab shall
not be less than 60 mm.
5.13.7 The pile should project 50 mm into the cap concrete.
5.14 The design of grade beams if used shall be as given in IS : 2911
( Part 3 )-1980t.
6. MATERIALS
6.1 Cement-The cement used shall conform to the requirements of
IS : 269-19761, IS : 455-19769, IS : 8041-1978/l, IS : 1@9-197617, and
IS : 6909-1973** as the case may be.
*Code of practice for plain and reinforced concrete ( f/&drevision).
tCode of practice for design and construction of pile foundations : Part 3 Under-
reamed pile foundations ( f;rst r&ion ).
tSpecification for ordinary and low heat Portland cement ( fhird r&&n ).
§Specilication for Portland slag cement ( third rcei~ion ).
IlSpecification for rapid hardening Portland cement ( JFrsf r&ion ).
$5pecification for Portland-pozzolana cement ( second re&ion ).
**Specification for super-sulphated cement.
14

16.
IS : 2911 ( Part l/Set 4 ) - 1984
6.2 Steel - Reinforcement steel shall conform to IS : ‘1.72 ( Part 1 )-
1982*, IS : 1139-1966t, or IS : 1786-19661, or IS : 226-1975s.
6.3 Concrete
6.3.1 Materials and method of manufacture for cement concrete shall
in general be in accordance with the relevant requirements given in IS :
456-197811. The stresses in concrete due to working load and during
handling, pitching and driving of the pile should not exceed than those
stipulated in IS : 456-197811 according to the grade of concrete used and
having due regard to the age of piles at the time of handling.
6.3.2 The grade of concrete should be preferably not less than M25.
7. WORKMANSHIP
7.1 As far as possible in-situ extensions shall be avoided. The casting
yard for all concrete piles should preferably be so arranged that they can
be lifted directly from their beds and transported to the piling frame with
a minimum of handling. The casting yard should have a well-drained
surface to prevent excessive or uneven settlement due to softening during
manufacture and curing.
7.2 As far as practicable each longitudinal reinforcement shall be in one
kngth. In cases where joints in reinforcing bars cannot be avoided, the
joints in bars shall be staggered. The hoops and links for reinforcement
shall fit tightly against longitudinal bars and be bound to them by welding
or by tying with mild steel wire, the free ends of which should be turned
into the interior of the pile. The longitudinal bars may be held apart by
temporary or permanent spreader forks not more than 1.5 m apart.
The reinforcement shall be checked for tightness and position immediately
before concreting.
7.3 Casting and Curing
7.3.1 The piles should be cast in a continuous operation from end to
end of each pile. The concrete should be thoroughly compacted against
the forms and around the reinforcement by means of immersion and/or
shutter vibrators. The faces of the pile including those exposed at the
*Specification for mild steel and medium tensile steel bars and hard drawn steel
wires for concrete reinforcement: Part 1 Mild steel and medium tensile stwl bus ( third
rcoision ).
$Specification for hot-rolled mild steel medium tensile steel and high yield
strength steel deformed bars and concrete reinforcement ( revised ).
&Specification for cold-worked steel high strength deformed bars for concrete
reinforcement ( second rwision ).
$Specilicatiol for structural steel ( standard quality ) ( fifrh reoision).
/[Code of practice for plain and reinforced concrete ( third r&ion ).
15

17.
IS : 2911 ( Part l/Set 4 ) - 1984
top of pile should be dense as far as possible. Immediately on completion
of the casting the top surface should be finished level without excessive
trowelling. Care should be taken to ensure that vibration from adjoining
works does not effect the previously placed concrete for piles during the
setting period.
7.3.1.1 All shuttering shall be placed on firm supports capable of
withstanding the loads of shuttering, wet concrete and incidental load of
workmen, so that cast piles are straight and free from deformations. The
shuttering shall be coated with oil on the inside face.
7.3.2 Though from consideration of speed and economy precast
concrete piles will have to be placed with the least possible delay after
casting, it shall be kept in mind that a thorough curing and hardening is
necessary before the piles are placed and proper schedule to take care of
this shall be decided for the operations of casting, stacking and placing.
The most important factors effecting the time of curing are the method of
curing, weather during hardening, probable hardness of placing and the
method of lifting and pitching.
7.3.4 Before the operation of handling the piles, the minimum periods
counted from the time of casting as given in IS : 456-1978* shall be
followed.
7.4 Sorting and Hand&g
7.4.1 Piles shall be stored on firm ground free from liability to unequal
subsidence or settlement under the mass of the stack of piles. The piles
shall be placed on timber supports which are truly level and spaced so as
to avoid undue bending in the piles.
above the other.
The support shall be vertically one
Spaces shall be left round the piles to enable them to be
lifted without difficulty. The order of stacking shall be such that the
older piles can be withdrawn for placing without disturbing the newer
piles. Separate stacks shall be provided for different lengths of piles.
Wherever curing is needed during storage, arrangements shall be made
to enable the piles to be watered if weather conditions so require. For
detailed precautions with regard. to curing operations reference may be
made to IS : 456-1978*.
7.4.2 Care shall be taken at all stages of transporting, lifting and handl-
ing of the piles that they are not damaged or cracked. During trans-
portation, the piles shall. be supported at the appropriate lifting holes
Provided for the purposes. If the piles are put down temporarily after
being lifted, they shall be placed on trestles of blocks located at the lifting
points.
*Code ofpractice for plain and reinforced concrete ( thirdreri~ion).
16

18.
IS : 2911 ( Part l/Set 4 ) - 1984
7.5 Control of Pile Installation
7.5.1 Bored precast piles shall be constructed by suitable choice of boring
and installation techniques; covering the manner of soil stabilization, that
is, use of casing and/or use of drilling mud and choice of boring tools in
order to permit a satisfactory installation of a pile at a given site. Sufficient
detailed information about tKe subsoil conditions is essential to predeter-
mine the details of the installation technique. The bottom end of the pile
shall have proper arrangements for cleaning and grouting.
7.5.2 Control of Alignment - Piles shall be installed as accurately as possi-
ble according to the designs and drawings either vertically or to the
specified batter. Greater care should be exercised in respect of installation
of single pile or piles in two pile groups. As a guide, for vertical piles a
deviation of 1.5 percent and for raker piles a deviation of 4 percent should
not be normally exceeded although in special cases a closer tolerance may
be necessary. Piles should not deviate more than 75 mm or D/4 which-
ever is less ( 75 mm or D/l0 whichever is more in case of piles having
diameter more than 600 mm ) from their designed positions at the work-
ing level. In the case of a single pile in a column the positional tolerance
should not be more than 50 mm or D/4 whichever is less ( 100 mm in case
of piles having diameter more than 600 mm ). Greater tolerance may be
prescribed for piles driven over water and for raking piles. For piles to be cut
off at a substantial depth ( below ground level ) or height ( above ground
level ), the design should provide for the worst combination of the above
tolerance in position and inclination. Iti case of piles deviating beyond
theqe limits and to such an extent that the resulting eccentricity cannot
be taken care of by a redesign of the pile cap of pile ties, the piles should
be replaced or supplemented by one or more additional piles. In case of
piles, with non-circular cross section ‘ D ’ should be taken as the dimensions
of the pile, ,along which the deviation is computed. In such casts the
permissible deviation in each direction should be different deprnding upon
the dimension of the pile along that direction.
7.6 Flushing - The central duct/hole shall be connected to a suitable
pump and water drilling fluid allowed to i-low through the bottom of the
pile removing loose material.
7.7 Grouting - Sand and cement grout mixed with water in a high
speed collidal mixer is to be fed into the pile with a grout pump of suit-
able capacity connected to the central duct through a manifold. A grout
of sand and cement with additives as necessary, of strength not less than
1 : 2 cement and sand ( see also Note under 1.1 ) suitable for pumping into
the annulus, may also be used. The temporary casing here used shall be
removed in stages with the rise of the level of grout. After final removal
of the temporary casing, the grout level shall be brought up to the top by
pouring in additional grout as required.
17

19.
IS : 2911( Part l/Set 4 ) - 1984
7.8 Defective Pile - In case, defective piles are formed, they shall be
removed or left in place whichever is convenient without affecting perfor-
mance of the adjacent piles or the cap as a whole. Additional piles shall be
provided to replace them,
7.9 Any deviation from the designed location alignment or load capacity
of any pile shall be noted and adequate measures taken well before the
concreting of the pile cap and plinth beam if the deviations are beyond
the premissible limit.
7.10 Recording of Data
7.1O.i A competent inspector shall be present to record the necessary
information during installation of piles and the data to be recorded shall
include:
a) the sequence of installation of piles in a group;
b) the dimensions of the pile including the reinforcement details and
mark of the pile;
c) the depth placed;
d) cut off level/working level; and
e) any other important observation.
7.102 Typical data sheet for facility of recording piling data are shown
in Appendix C.
7.11 Stripping Pile Heads
7.11.1 The concrete should be stripped to a level such that the remain-
ing concrete of a pile will project minimum 50 mm into the pile cap. The
effect of this projection on the position of any reinforcement in the pile
cap should be considered in design. The pile reinforcement should be left
with adequate projecting length above the cut off level for proper embed-
ment into the pile cap. Exposing such length should be done carefully to
avoid shattering or otherwise damaging the rest of the pile. Any cracked
or defective concrete should be cut away and made good with new concrete
properly bonded to the old.
7.12 Lengthening Piles - Where a pile is to have another length cast
on to it before or during placing the longitudinal reinforcement should
preferably be jointed by full penetration butt welding. The concrete at the
top of the original pile should be cut down to expose not less than 200 mm
of the bars. The bars should be held accurately and rigidly in position
during welding. Where facilities at site are insufficient to make good butt
welding practicable the ,joint may be made by lapping. The reinforcement
at the head of the pile will need to be exposed for a distance of 40 times
the bar diameter and the new bars overlapped for this distance. If the
bonds are lapped, spot welding shall be done. As an alternative special
bolt and nut joints may be provided.
18

20.
IS : 2911 ( Part l/&c 4 ) - 1984
APPENDIX A
( Claflse 5.3.1.1 )
LOAD CARRYING CAPACITY-STATIC FORMULA
A-l. PILES IN GRANULA& SOILS
A-l.1 The ultimate bearing capacity ( Q,, ) of piles in granular soils is
given by the following formula:
where
A, = cross-sectional area of pile toe in in cm*;
D = stem diameter in cm;
y = effective unit weight of soil at pile toe m kgf/cms;
P,, = effective overburden pressure at pile toe in kgf/cms;
N, and N, = bearing capacity factors depending upon the angle of
internal friction 4 at toe;
c
n
i=l
summation for n layers in which pile is installed;
K = coefficient of earth pressure;
PDi = effective overburden pressure in kg/cm* for the Gh layer
where i varies from 1 to n;
8 = angle of wall friction between pile and soil, in degrees
( may be taken equal to # ); and
A 81= surface area of pile stem in cm* in the Sh layer where
i varies from 1 to n.
NOTE 1 - Nr factor can be taken for general shear failure as per IS : 6403-1981.
NOTE 2 - .Nq factor will depend, apart from nature of soil on the type of pile
and its method of construction, for bored piles, the value of .Nq corresponding to
angle of shearing resistance 4 are given in Fig. 1. This is based on Berezantseu’s
curve for D/B of 20 up to 4 = 35’ and Vesic’s curves beyond 4 = 35”.
NOTE 3 - The earth pressure coefficient K depends on the nature of soil strata,
type of pile and its method of construction.
K values between 1 and 2 should be used.
For bored piles in loose medium sands;
*Code of practice far determination of bearing capacity of shallow foundations
(first rrvision) .
19

21.
IS 82911( Part lpc 4 ) - 1984
NOTE 4 -The angle of wall friction may be taken equal to angle of shear
resistance of soil.
NOTE 5 - In working out pile capacities using static formula, for piles longer
than 15 to 20 pile diameter, maximum effective overburden at the pile tip should
correspond to pile length equal to 15 to 20 diameters.
A-2. PILES IN COHESIVE SOILS
A-2.1 The ultimate bearing capacity of piles ( Q,, ) in cohesive soil is
given by the following:
QP = A,. JV,.C, + a. CA,
where
A, = cross sectional area of pile toe in ems,
fl, = bearing capacity factor usually taken as 9,
C, = average cohesion at pile tip in kg/cm*,
a = reduction factor,
c = average cohesion throughout the length of pile in kg/cmS,
and
A8” surface area of pile shaft in ems.
Nom 1 - The following values of (xmay be taken depending upon the consis-
tency of the soils:
Consislcncy Jv Value Value of a
Soft to very soft <4 0’7
Medium 4 to 8 0’5
Stiff 8to 15 0’4
Stiff to hard > 15 0.3
NOTE 2 - (a) Static formula may be used as a guide only for bearing capacity
estimate. Better reliance may be put on load teat on piles.
(b) For working out safe load a minimum factor of safety 2.5 should be used
on the ultimate bearing capacity estimated by static formulae,
NOTE 3 - OTmay be taken to vary from 0’5 to 0’3 depending upon the consis-
tency of the soil. Higher values of up to one may be used for softer soils, provided
the roil is not sensitive.
A-2.2 When full static penetration data is available for the entire depth,
the following correlations may be used as a guide for the determination of
shaft resistance of a pile.
21

30.
AMENDMENT NO. 1 OCTOBER 1987
TO
IS : 2911( Part 1/Set 4 )-1984 CODE OF PRACTICE FOR
DESIGN AND CONSTRUaION OF PILE
FOUNDATION’
PART 1 CONCRETE PILES
Section 4 Bored Precast Concrete Piles
( Page 10, clause 5.5.2, last two sentences ) - Substitute the follow-
ing for the existing matter:
‘A recommended method for the determination of depth of fixity,
lateral deflection and maximum ben
is given in Appendix B for fully ori artially embedded piles. OtherB
g moment required for design
accepted methods, such as the method of Reese and Matlock for fully
embedded piles may also be used.’
( Page 15, clause 6.2, li?je 2 ) - Substitute ‘ JS : 1786-1985$ ‘for
‘IS : 1139-1966t, or IS : 1786-1966$‘.
( Page 15, clause 6.3.2,) - Add the following new clause after 6.3.2:
‘6.3.3 For the concrete, water and aggregates specifications laid down
in IS : 456-197811 shall be ‘followed in general. Natural rounded
shingle of appropriate size may also be used as coarse aggregate. It
helps to give high slump with less water-cement ratio. For tremie
concreting aggregates having nominal size more than 20 mm should not
be used.’
( Page 15, foot-notes marked with ‘ t y and ‘ t ’ mark ) - Substi-
tute the following for the existing foot-notes:
‘SSpecification for high strength deformed steel bars and wires for concrete
reinforcement ( third revision ).’
( Page 17, clause 7.5.2, fourth and Jifth sentences ) - Substitute
‘D/6 -‘for ‘ D[4 ‘, at both the places.
( Pages 23 and 24, Appendix B including Fig. 2
the following for the existing appendix and figures:
and 3 ) - Substitute
1

31.
‘APPENDIX B
( Clause 5.5,2)
DETERMINATION OF DEPTH OF FLXSTY, LATERAL DEFLECTION
AND MAXIMUM MOMENT OF LATERALLY LOADED PILES
B-l. DETERMINATION OF LATERAL DEFLECTION AT THE PILE
HEAD AND DEPTH OF FIXITY
B-l.1 The long flexible pile, fully or partially embedded, is treated as a
cantilever fixed at some depth below the ground level ( see Fig. 2 ).
2J -
-FREE HEAD PILE
-a. ----_
PILES IN SANDS
AND NORMALLY LOADEO
CLAY5
L,/R OR Lj/l
FIG. 2 DETERMINATIONOFDEPTH FIXITY
B-1.2 Determine the depth of fixity and hence the equivalent length of
the cantilever u$ng the plots given in Fig. 2.
where
and R = 4
J
iz
z ( Kt and Kg are constants given in
Tahlds I and 2 belo: E is the Young’s modulus of the
pile material in kg/c& and Z is the moment of inertia of
the pile cross-section in cm4 >.
NOTE- Fig. 2 ishvnlid for Iong flexible piles where the embedded length &, is
2 4R or 47-s
1: